Thin film magnetic head which prevents errors due to electric discharge

ABSTRACT

A thin film magnetic head includes a slider and a thin film magnetic transducing element, wherein the slider is provided with an insulating film on a surface of an electric conductive substrate, the thickness of the insulating film being in a range of 0.5 μm-3 μm, and the thin film magnetic transducing element is formed on the insulating film and has a thin film magnetic circuit including a magnetic film and a coil film.

This application is a Continuation of application Ser. No. 07/928,297,filed on Aug. 12, 1992, now abandoned.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a flying type thin film magnetic head.More particularly, it relates to a thin film magnetic head capable ofpreventing an electric discharge resulted from accumulation of anelectric charge in a capacitor which is formed between a coil film and amagnetic film which constitute a thin film magnetic transducing element.

Discussion of Background

A typical thin film magnetic head comprises a slider and a thin filmmagnetic transducing element. The slider has an insulating film such asan alumina film having a thickness of 10 μm or more on a surface of aconductive substrate and the thin film magnetic transducing element isformed on the insulating film. The thin film magnetic transducingelement has a coil film having an electric potential and a magnetic filmfor forming a thin film magnetic circuit in association with the coilfilm. In such structure, a capacitor is formed between the magnetic filmand the coil film.

On the other hand, a small-sized HDD commercialized lately is adapted touse a partial power source of a 5 volt power source for areading/writing IC so that a 5-volt power source and a 12-volt powersource which are used for power sources for a personal computer can beutilized in consideration of using the personal computer. Accordingly,the thin film magnetic head is always biased by a constant voltage,specifically, a positive voltage of 2.5 volts. In this case, an electriccharge is accumulated in the capacitor from a specified direction due toa bias voltage.

The electric charge accumulated in the capacitor is discharged due tothe contact of the pole portion to a recording medium, whereby apotential at the magnetic film varies. A change of electric potential atthe magnetic film produces common mode noises, and an error takes placein the data for reading. Regarding a technique to eliminate suchundesired electric discharge, there is a publication such as U.S. Pat.No. 4,987,514. The publication discloses that an electric discharge isprevented by making a bias potential to the thin film magnetic headequal to the electric potential at a recording medium.

In the conventional technique, however, it is necessary to provide anelectric potential equalizing means to the recording medium rotated inorder to equalize the electric potential of the medium to a biaspotential of the thin film magnetic head. Accordingly, the constructionof the magnetic disk device is complicated and large-sized as well ascost increased.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a thin film magnetichead and a thin film magnetic head device using such magnetic head inwhich influence to the thin film magnetic circuit can be greatly reducedand an electric discharge suppressing function can be obtained in astable manner.

The foregoing and other objects of the present invention have beenattained by providing a thin film magnetic head which comprises a sliderand a thin film magnetic transducing element, wherein the slider isprovided with an insulating film on a surface of an electricallyconductive substrate, the thickness of the insulating film being in arange of 0.5 μm-3 μm, and the thin film magnetic transducing element isformed on the insulating film and has a thin film magnetic circuitincluding a magnetic film and a coil film.

According to the present invention, there is provided a thin filmmagnetic head which comprises a slider and a thin film magnetictransducing element, wherein the slider has an electrically conductivesubstrate as the major portion, and the thin film magnetic transducingelement comprises a magnetic film and a coil film, the magnetic filmbeing directly formed on the electrically conductive substrate.

According to the present invention, there is provided a thin filmmagnetic head which comprises a slider and a thin film magnetictransducing element, wherein the slider comprises an electricallyconductive substrate as the major portion and an insulating film formedon the electrically conductive substrate, and the thin film magnetictransducing element comprises a magnetic film and a coil film and isformed on the insulating film so that at least a part of the magneticfilm is in direct contact with the electrically conductive substratethrough a hole formed in the insulating film.

BRIEF DESCRIPTION OF DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is a perspective view of a thin film magnetic transducing elementused for an embodiment of the thin film magnetic head according to thepresent invention;

FIG. 2 is an enlarged cross-sectional view of the thin film magnetictransducing element shown in FIG. 1;

FIG. 3 is a perspective view of a thin film magnetic transducing elementof a second embodiment of the thin film magnetic head according to thepresent invention;

FIG. 4 is an enlarged cross-sectional view of the thin film magnetictransducing element shown in FIG. 3;

FIG. 5 is an enlarged cross-sectinal view of a thin film magnetictransducing element used for a third embodiment of the thin filmmagnetic head of the present invention;

FIG. 6 is an enlarged cross-sectional view of a thin film magnetictransducing element of a fourth embodiment of the thin film magnetichead according to the present invention;

FIG. 7 is a perspective view of another embodiment of the thin filmmagnetic head of the present invention; and

FIG. 8 is a perspective view of another embodiment of the thin filmmagnetic head of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to the drawings wherein the same reference numerals designatethe same or corresponding parts. FIG. 1 is a perspective view showing anembodiment of the thin film magnetic head including a thin film magnetictransducing element according to the present invention, and FIG. 2 is anenlarged cross-sectional view partly omitted of the thin film magnetictransducing element. The Figures are to show general construction of thethin film magnetic transducing element, and the dimensions of structuralelements are exaggerated. In FIGS. 1 and 2, numeral 1 designates aslider, 2 designates a thin film magnetic transducing element.

The slider 1 comprises an electrically conductive substrate 101 made ofa material such as Al₂ O₃ -TiC and an insulating film 102 made of amaterial such as alumina which is formed on the substrate 101. In theslider 1, the thickness of the insulating film 102 is in a range of from0.5 μm-3 μm. The thin film magnetic transducing element 2 is disposed onthe insulating film 102. The thin film magnetic transducing element 2comprises a magnetic film including a lower magnetic film 21 and anupper magnetic film 22 and coil films 23.

The slider 1 shown in FIG. 1 is provided with two rails 103 at thesurface facing a recording medium, and the surfaces of the rails 103 areutilized as air bearing surfaces 105.

The slider 1 may be of a type wherein the surface facing a recordingmedium has no rail portions and is a flat air bearing surface.

In the thin film magnetic transducing element 2 comprising the lowermagnetic film 21, the upper magnetic film 22 and the coil films 23, thelower magnetic film 21 and the upper magnetic film 22 are usually madeof a material such as permalloy, and they have pole portions 211, 221 attheir one end portions which form a transducing gap. The pole portions211, 221, extend backwardly to form yoke portions 212, 222 so that amagnetic circuit is formed. The pole portions 211, 221 are spaced apartfrom each other by interposing a gap film 24 made of a material such asalumina. The coil films 23 are formed in a spiral form around theconnecting portion of the lower magnetic film 21 and the upper magneticfilm 22. There are provided insulating films 251 through 253 between thecoil film 23 and the lower magnetic film 21 and between the coil film 23and the upper magnetic film 22. The insulating films 251-253 aregenerally made of an organic resin such as novolak resin. Numeral 26designates a protective film such as alumina, numerals 27, 28 designateterminal electrodes, and numerals 271, 281 designate lead electrodes.

As described above, since the thickness of the insulation film 102 is ina range of 0.5 μm-3 μm, the insulating resistance of the insulating film102 is fairly low in comparison with a conventional technique in whichthe film thickness of the insulating film is 10 μm or higher. The lowermagnetic film 21 and the upper magnetic film 22 are electricallyconnected to the electric conductive substrate 101, which is kept at theground potential, by interposing the insulating film 102 having a lowerinsulation resistance, and accordingly, potential difference between themagnetic films 21, 22 and the insulating film 102 is reduced to a valuewhich is determined by the insulation resistance of the insulating film102 and a leakage current. Accordingly, a possibility of an electricdischarge between a recording medium (not shown) and the pole portions211, 221 of the magnetic films 21, 22 resulted from the accumulation ofan electric charge in a parastic capacitor, and a possibility of anerror in the data to be read which is caused by the electric discharge,can be reduced.

In the above-mentioned embodiment, since the thickness of the insulatingfilm 102 is in a range of 0.5 μm-3 μm, an insulation resistance requiredfor the thin film magnetic circuit can be assured. Further, since thecoil films 23 are insulated by means of the organic insulating resinousfilms 251-253, an electric insulation required for the coil films issufficient even though the thickness of the insulating film 102 is thinas described above.

Further, it is enough that the thickness of the insulating film 102 ofthe slider 1 is controlled. It is no danger of causing adverse effect tothe thin film magnetic circuit. Further, since any additional step ofmanufacturing the thin film magnetic head is required, it isadvantageous in that generally used steps for manufacturing can beutilized.

The above-mentioned embodiment provides the following advantages.

(a) Since the thickness of the insulating film of the slider is in arange of 0.5 μm-3 μm, and the thin film magnetic transducing element isdisposed on the insulating film, there can be provided a thin filmmagnetic head capable of reducing a possibility of an electric dischargebetween a recording medium and the pole portions of the magnetic filmresulted from the accumulation of an electric charge in the parasticcapacitor and a possibility of an error in data to be read due to theelectric discharge, in comparison with a conventional technique having afilm thickness of the insulating film of 10 μm or more.

(b) Since the thickness of the insulating film is in a range of 0.5 μm-3μm, the insulation resistance required for the thin film magneticcircuit can be maintained.

(c) Since it is enough to control the thickness of the insulating filmof the slider, there can be provided a thin film magnetic head allowingeasy manufacture by using ordinary manufacturing steps without requiringspecial manufacturing steps while there is no danger of causing adverseeffect to the thin film magnetic circuit.

FIG. 3 is a perspective view of another embodiment of the thin filmmagnetic head of the present invention in which a thin film magnetictransducing element is shown in detail, and FIG. 4 is an enlargedcross-sectional view of the thin film magnetic transducing element. InFIGS. 3 and 4, reference numeral 1 designates a slider and numeral 2designates a thin film magnetic transducing element.

The slider 1 comprises an electrically conductive substrate, as themajor portion, which is made of a material such as Al₂ O₃ -TiC. The thinfilm magnetic transducing element 2 is directly formed on a surface ofthe electrically conductive substrate 101. In a conventional technique,an insulating film such as alumina was formed on the substrate.

The slider 1 may be of a type wherein rails are formed in the surface ofthe slider facing a recording medium, or a type wherein the mediumfacing surface of the slider 1 is flat.

The thin film magnetic transducing element 2 comprises a lower magneticfilm 21, an upper magnetic film 22 and coil films 23. In the secondembodiment, the lower magnetic film 21 is directly formed on an endsurface of the electrically conductive substrate 101. The constructionof the thin film magnetic transducing element except for theabove-mentioned is the same as that of the first embodiment, andaccordingly, description is omitted.

In the second embodiment, since the slider 1 comprises the electricallyconductive substrate 101 as its major portion, and the lower magneticfilm 21 of the thin film magnetic transducing element 2 is formeddirectly on the electrically conductive substrate 101, the lowermagnetic film 21 and the upper magnetic film 22 are kept at the sameelectrically potential as the electric conductive substrate 101 whichhas the ground potential. Accordingly, there is no danger that anelectric discharge takes place between a recording medium (not shown)and the pole portions 211, 221 of the magnetic films 21, 22 due to theaccumulation of an electric charge even when the electric charge isaccumulated in the capacitor between the coil films 23 and the upper andlower magnetic films 21, 22. Further, there is no danger of causingadverse effect in terms of magnetism to the thin film magnetic circuit.

Since the coil films 23 are insulated by means of the organic insulatingresinous films 251-253, the electric insulation required for the coilfilms 23 can be assured even though the lower magnetic film 21 is formedin direct contact with the electrically conductive substrate 101.

Lead electrodes 271, 281 and bonding electrodes 27, 28 connected to thecoil films 23 are electrically insulated from the electricallyconductive substrate 101 because insulating films of a material such asalumina are provided underneath such elements.

The second embodiment of the present invention provides the followingadvantages.

(a) Since the major portion of the slider is formed of the electricallyconductive substrate and the magnetic layer of the thin film magnetictransducing element is disposed directly on the electrically conductivesubstrate, a thin film magnetic head free from occurrence of an electricdischarge between a recording medium and the pole portion of themagnetic film due to the accumulation of an electric charge in thecapacitor and an error in data to be read which is caused by theelectric discharge, can be provided.

(b) A thin film magnetic head having an electric discharge preventingstructure by which there is no adverse effect in terms of magnetism tothe thin film magnetic circuit, can be provided.

FIG. 5 is an enlarged cross-sectional view of an embodiment of the thinfilm magnetic transducing element of the thin film magnetic head of thepresent invention. In FIG. 5, numeral 1 designates a slider and numeral2 designates a thin film magnetic transducing element.

The slider 1 comprises an electrically conductive substrate 111 as themajor portion which is made of a material such as Al₂ O₃ -TiC, and aninsulating film 112 made of a material such as alumina which is formedon a surface of the electrically conductive substrate 111.

The thin film magnetic transducing element 2 comprises a lower magneticfilm 21, an upper magnetic film 22 and coil films 23. The lower magneticfilm 21 is formed in direct contact with the electrically conductivesubstrate 111 through a hole 121 formed in the insulating layer 112. Thelower magnetic film 21 and the upper magnetic film 22 are made of amaterial such as permalloy; they respectively have pole portions 211,221 at end portions by which a transducing gap is formed; and theyrespectively have yoke portions 212, 222. The rear portions 213, 223 ofthe yoke portions 212, 222 which are opposite the pole portions 211,222, are connected to each other so as to form a magnetic circuit. Thepole portions 211, 222 are separated from each other by means of a gapfilm 24 made of a material such as alumina. The lower magnetic film 21has the yoke portion 212 the major portion of which is formed on theelectrically conductive substrate 111 through the hole 121 formed in theinsulating film 112, and the pole portion 211 of the lower magnetic film21 is supported by an insulating film portion 122 remaining at an endportion of the electrically conductive substrate 111. The surface levelof the yoke portion 212 is stepwisely depressed from the surface levelof the pole portion 211.

The coil films 23 are arranged so that they are extended in a spaceformed between the yoke portions 212, 222 and they are supported by theorganic insulating films 251-253 so as to be wound around the connectingportion of the yoke portions 212, 222. The organic insulating films251-253 are generally made of an organic resinous material such asnovolak resin. Numeral 26 designates a protective film such as alumina.

In the third embodiment of the present invention, since the lowermagnetic film 21 of the thin film magnetic transducing element 2 isformed in direct contact with the electrically conductive substrate 111through the hole 121 formed in the insulating film 112, the lowermagnetic film 21 and the upper magnetic film 22 are kept at the samepotential as the electrically conductive substrate 111 which has theground potential. Accordingly, there is no possibility of an electricdischarge between a recording medium (not shown) and the pole portions211, 221 of the magnetic films 21, 22 resulting from the accumulation ofan electric charge in the capacitor between the coil films 23 and thelower and upper magnetic films 21, 22. Further, there is no danger ofresulting adverse effect in terms of magnetism to the thin film magneticcircuit.

Further, since the thin film magnetic transducing element 12 is providedon the insulating film 112, the coil films 23 of the thin film magnetictransducing element 2 is insulated not only by the organic insulatingfilms 251, 252 but also the insulating film 112.

FIG. 6 is an enlarged cross-sectional view of an embodiment of the thinfilm magnetic transducing element of the thin film magnetic head of thepresent invention. In FIG. 6, the same reference numerals as in FIG. 5designate the same or corresponding parts. In this embodiment, the lowermagnetic film 21 is formed in direct contact with the electricallyconductive substrate 111 through a hole formed in the insulating film112. The surface level of the yoke portion 212 is substantially flushwith the surface level of the pole portion 211.

In the above-mentioned thin film magnetic head of the present invention,the slider 1 can be formed to have a different structure. FIGS. 7 and 8show two examples of structure.

In FIG. 7, the slider 1 has two rails 103, 104 at the surface facing arecording medium and the surfaces of the rails 103, 104 are utilized asair bearing surfaces 105, 106. Numerals 27, 28 designate bondingelectrodes connected to the coil films 23, and numerals 271, 281designate lead electrodes. These electrodes are provided on theinsulating film 112 as an element of the slider 1. Accordingly, theinsulating film 112 provides a sufficient insulation between theelectric conductive substrate 111 and these electrodes 27, 28, 271 and281.

FIG. 8 shows such slider 1 that the surface of the slider facing arecording medium is a flat air bearing surface 107 without having railportions. The bonding electrodes 27, 28 and the lead electrodes 271, 281are provided on the insulating film 112 by which a sufficient electricalinsulating can be maintained between the electrically conductivesubstrate 111 and these electrodes.

The third and subsequent embodiments of the present invention providesthe following advantages:

(a) The thin film magnetic transducing element is so arranged that atleast a portion of the magnetic film is formed in direct contact withthe electrically conductive substrate through a hole formed in theinsulating film of the slider. Accordingly, there can be provided a thinfilm magnetic head which suppresses an electric discharge between arecording medium and the pole portions of the magnetic films due to theaccumulation of an electric charge in the capacitor and an error 2 datato be read which is caused by the electric discharge.

(b) A thin film magnetic head having an electric discharge preventingstructure in which there is no adverse effect in terms of magnetism tothe thin film magnetic circuit can be provided.

(c) The insulating film is formed on a surface of the electricallyconductive substrate, the thin film magnetic transducing element isprovided on the insulating film, and the magnetic film of the thin filmmagnetic transducing element is formed in direct contact with theelectrically conductive substrate through a hole formed in theinsulating film. Accordingly, a thin film magnetic head providing asufficient electrical insulation by the insulating film between theelectrically conductive substrate and the coil films of the thin filmmagnetic transducing element as well as the lead electrodes and thebonding electrodes, can be provided.

In the above-mentioned embodiments, description has been made as to anin-plane recording/reproducing thin film magnetic head. However, thepresent invention is applicable to a vertical recording/reproducing thinfilm magnetic head.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A thin film magnetic head which comprises:aslider and a thin film magnetic transducing element, wherein said slideris provided with an insulating film directly formed on a surface of anelectrically conductive substrate, a thickness of said insulating filmbeing in the range of 0.5 μm-3 μm, and said thin film magnetictransducing element is formed on said insulating film and has a thinfilm magnetic circuit including a magnetic film and a coil film, whereinsaid insulating film is formed between said electrically conductivesubstrate and said magnetic film and allows an equipotential to beformed therebetween because of its thickness, and wherein said coil filmis electrically insulated by an organic insulating resinous film havingan insulation resistance sufficient to electrically insulate said coilfilm in view of the thickness of said insulating film.
 2. The thin filmmagnetic head according to claim 1, wherein the magnetic film comprisesa lower magnetic film and an upper magnetic film;the lower and uppermagnetic films having respectively a pole portion which constitutes atransducing gap, and a yoke portion contiguous with the pole portion,the pole portions facing one another with a space therebetween and beingconnected to each other at a position opposing the transducing gap; thesubstantial portion of the yoke portion in the lower magnetic film beingin contact with the electrically conductive substrate through a holeformed in said insulating film; the pole portion of a lower magneticfilm being supported by the insulating film; and the coil film beingarranged so as to extend through the space formed between the yokeportions and to be wound around the connected portion of the yokeportions, and being supported by an organic insulating film.
 3. The thinfilm magnetic head according to claim 2, wherein the lower magnetic filmis so arranged that the surface level of the yoke portion is stepwiselydepressed from the surface level of the pole portion.
 4. The thin filmmagnetic head according to claim 2, wherein the lower magnetic film isso arranged that the upper surface of the yoke portion is substantiallyflush with the surface level of the pole portion.
 5. A thin filmmagnetic head which comprises:a slider and a thin film magnetictransducing element, wherein said slider comprises an electricallyconductive substrate as its major portion and an insulating film formedon said electrically conductive substrate, a thickness of saidinsulating film being in the range of 0.5 μm-3 μm, and said thin filmmagnetic transducing element comprises a magnetic film and a coil filmand its formed on said insulating film so that at least a part of saidmagnetic film is in direct contact with said electrically conductivesubstrate through a hole formed in said insulating film, wherein saidinsulating film is formed between said electrically conductive substageand said magnetic film and an equipotential is formed therebetweenbecause of said direct contact therebetween via said hole, and whereinsaid coil film is electrically insulated by an organic insulatingresinous film having an insulation resistance sufficient to electricallyinsulate said coil film in view of the thickness of said insulatingfilm.